Explain how solving $2x<-8$ is different from solving $-2x<8$ .

When we divide by a negative value, the sign for the inequality changes.

Step-by-step explanation:

2x < -8, to solve we would divide by 2 and receive x < -4. However, in solving -2x < 8, we would divide by negative 2, which would result in x > -4. Clearly, these sequences provide opposite answers and that is a rule to inequalities, that when dividing by a negative number, we must flip the less than/greater than sign.

16.9 times 2.85

step-by-step explanation:

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.